Abstract. Six receptor proteins, with molecular masses ranging from 94 to 27kDa, that bind to Escherichia coli K88ab fimbriae were recovered from brush border membranes and were detected after solubilization with Triton X-114. The recovery of these receptor proteins in the aqueous phase suggests their peripheral localization. The 63-, 60- and 33-kDa K88ab binding proteins were recovered using gel-filtration chromatography of the aqueous phase.